JPH05223414A - Refrigerating device - Google Patents

Abstract

PURPOSE:To provide a refrigerating device capable of performing an accurate sensing of a lack of refrigerant in a refrigerating cycle and further capable of performing an assurance of cooling performance and a protection of a refrigerant compressor through a low cost means. CONSTITUTION:A gas-liquid ratio sensing device 2 acting as means for sensing a lack of refrigerant is arranged between a receiver 7 and an expansion valve 8 of a refrigerating cycle 1. As the lack of refrigerant is detected by the gas- liquid ratio sensing device 2, an alarm lamp 26 is lit through a control circuit 25. In the case that upon detecting of the lack of refrigerant, the refrigerant compressor 4 is operated continuously for more than the predetermined time, an electrical excitation for a solenoid clutch 3 is turned off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus provided with a refrigerant shortage detecting means for detecting a refrigerant shortage in a refrigeration cycle, and is suitable for use in, for example, a vehicle air conditioner.

[0002]

2. Description of the Related Art Conventionally, as a method for detecting a refrigerant shortage in a refrigeration cycle adopted in a vehicle air conditioner or the like, for example, in a vehicle air conditioner disclosed in Japanese Patent Laid-Open No. 59-1971, An SH switch (superheat switch) that detects a predetermined degree of superheat is provided on the low pressure side, and a temperature switch that detects the refrigerant temperature is provided on the high pressure side. Techniques for stopping the driving of the compressor have been proposed. Further, the refrigerating apparatus disclosed in Japanese Patent Laid-Open No. 56-105281 is provided with an SH switch for detecting a two-step superheat degree, and this SH switch detects the first-step superheat degree, so that the refrigerant charging amount is increased. That the cooling capacity has begun to decrease due to lack of air conditioner and that the second stage superheat is detected to notify that it is in a dangerous state considering the durability of the refrigerant compressor due to insufficient refrigerant. You can

[0003]

However, as in the former example of the prior art, using two switches, an SH switch and a temperature switch, to detect a refrigerant shortage causes an increase in the cost of the refrigeration cycle, especially in a vehicle. It is disadvantageous when mounted. Further, when the shortage of the refrigerant is detected by using the SH switch that detects the two-stage degree of superheat, as in the latter conventional example, the contact stroke is shortened due to the structure of the SH switch, so that malfunction easily occurs. However, there was a problem that reliability remained a problem. The present invention has been made based on the above circumstances, and an object thereof is to detect a refrigerant shortage in a refrigeration cycle with high accuracy, and after the refrigerant shortage is detected, ensure the cooling performance and protect the refrigerant compressor at the same time. It is to provide a refrigerating device that enables low cost means.

[0004]

In order to achieve the above object, the present invention provides a refrigerating cycle having a refrigerant compressor for circulating a refrigerant, and a refrigerant charging amount in the refrigerating cycle during operation of the refrigerating cycle. Insufficient refrigerant detection means for detecting as insufficient refrigerant when the amount has decreased to a predetermined amount, when insufficient refrigerant is detected by the insufficient refrigerant detection means, warning means for warning that, and insufficient refrigerant by the insufficient refrigerant detection means Is detected, the control means for stopping the operation of the refrigerant compressor when the refrigerant compressor operates continuously for a predetermined time or longer is a technical means.

[0005]

In the refrigerating apparatus of the present invention having the above structure, when the refrigerant filling amount in the refrigerating cycle decreases to a predetermined amount, the refrigerant shortage detecting means detects that the refrigerant is insufficient, and the warning means gives a warning to that effect. Furthermore, after the refrigerant shortage is detected, when the refrigerant compressor continuously operates for the possession time or longer, the operation of the refrigerant compressor is stopped through the control means to protect the refrigerant compressor. As a result, the cooling capacity can be secured within a predetermined time after the lack of the refrigerant is detected. Even if the refrigerant shortage is detected, for example, when the refrigerant compressor repeatedly turns on and off, the continuous operation time (on time) does not reach the predetermined time, so the operation of the refrigerant compressor is stopped. There is no such thing.
In other words, even if a predetermined time has elapsed after the lack of refrigerant was detected, continuous operation does not occur due to the off time,
It is not necessary to stop the operation of the refrigerant compressor particularly because of concerns about durability.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the refrigerating apparatus of the present invention will be described with reference to FIGS. FIG. 1 is a refrigeration cycle diagram when the present invention is used in a vehicle air conditioner. The vehicle air conditioner of this embodiment includes a gas-liquid ratio detection device 2 (coolant shortage detection means of the present invention) for detecting a refrigerant shortage of the refrigeration cycle 1 which is a cooling means. Refrigeration cycle 1
A refrigerant condenser 6 that condenses and liquefies the high-temperature and high-pressure refrigerant discharged from the refrigerant compressor 4 by receiving the air blown from the refrigerant compressor 4 and the condensation fan 5 driven by the vehicle engine via the electromagnetic clutch 3. It comprises a receiver 7 provided downstream of the condenser 6, an expansion valve 8 for decompressing and expanding the supplied refrigerant, and a refrigerant evaporator 10 for evaporating the refrigerant decompressed by the expansion valve 8 in response to the blowing of the blower 9. Each of the functional parts has a well-known structure in which it is annularly connected by a refrigerant pipe 11.

The gas-liquid ratio detecting device 2 is, as shown in FIG.
A gas-liquid separation chamber 12 that is attached to a refrigerant pipe 11 a that is vertically provided between the receiver 7 and the expansion valve 8 and that separates and stores the sampled refrigerant into a gas component and a liquid component is provided. This gas-liquid separation chamber 12 has a refrigerant pipe 1
A stay 14 that is brazed to the opening 13 (see FIG. 3) formed in the pipe wall of the la 1 and the O-ring 1 is attached to the stay 14.
Formed by a case 16 screwed through
It communicates with the inside of the refrigerant pipe 11 a through a sampling passage 17, a first passage 18, and a second passage 19 formed in the stay 14.

The sampling passage 17 has a refrigerant pipe 11a.
It is a passage for introducing a part of the refrigerant flowing in the gas-liquid separation chamber 12 and is formed in a substantially central portion of the gas-liquid separation chamber 12 in the vertical direction. The first passage 18 is provided at a position higher than the sampling passage 17, and has one end at the gas-liquid separation chamber 12
It is opened toward the upper part inside and the other end is opened to the refrigerant pipe 11a. The second passage 19 is provided at a position lower than the sampling passage 17, one end thereof is opened toward the bottom of the gas-liquid separation chamber 12, and the other end is opened to the refrigerant pipe 11a. The stay 14 is provided so as to project into the refrigerant pipe 11a, and the thickness of the portion forming the first passage 18 and the second passage 19 is larger than the thickness of the portion forming the sampling passage 17. Therefore, the refrigerant pipe 11a is connected to the first passage 1
8 and the portion of the second passage 19 have a smaller flow passage cross-sectional area, forming a venturi. As a result, the refrigerant pipe 1
Part of the refrigerant flowing through 1a is guided from the sampling passage 17 into the gas-liquid separation chamber 12 along the flow based on the Venturi action in the portions of the first passage 18 and the second passage 19,
After being separated into a gas component and a liquid component in the gas-liquid separation chamber 12, the separated component returns to the refrigerant pipe 11 a from the first passage 18 and the second passage 19.

Here, where G1: the weight flow rate of the gas refrigerant passing through the first passage 18 and G2: the weight flow rate of the liquid refrigerant passing through the second passage 19, G1: G2 = 1: 9, the first passage 18 Are provided so as to have a predetermined passage resistance ratio with respect to the second passage 19. Therefore, when the gas-liquid weight ratio (gas weight / liquid weight) of the refrigerant flowing through the refrigerant pipe 11a is less than 1/9, the gas-liquid weight ratio of the refrigerant introduced from the sampling passage 17 into the gas-liquid separation chamber 12 Is also less than 1/9. At this time, since the liquid refrigerant exists in the gas-liquid separation chamber 12 up to the upper part in the gas-liquid separation chamber 12, the gas-liquid two-phase refrigerant flows in the second passage 1 through the first passage 18.
The liquid refrigerant returns to the refrigerant pipes 11a via 9 respectively. As the gas-liquid weight ratio of the refrigerant flowing in the refrigerant pipe 11a increases (the flow rate ratio of the gas refrigerant increases), the first
The flow rate ratio of the gas refrigerant in the passage 18 increases. At this time, only the liquid refrigerant still flows through the second passage 19. Further, when the flow rate of the gas refrigerant increases and the gas-liquid weight ratio of the refrigerant flowing through the refrigerant pipe 11a exceeds 1/9, the gas refrigerant in the gas-liquid separation chamber 12 cannot flow through the first passage 18 alone. .. As a result, the gas refrigerant also tries to flow out from the second passage 19, so that the liquid level in the gas-liquid separation chamber 12 becomes the second level.
It drops to the height of the passage 19.

A nylon float 22 (see FIG. 4) in which two magnets 20 and 21 are embedded is housed in the gas-liquid separation chamber 12. The float 22 is provided so as to float on the liquid surface of the liquid refrigerant, and floats up and down in the gas-liquid separation chamber 12 according to the displacement of the liquid surface in the gas-liquid separation chamber 12. As shown in FIG. 5, the reed switch 23 is fixed to the outer circumference of the case 16 by a holder 24. The reed switch 23 is located above the one magnet 20 embedded in the float 22,
It is fixed to the upper position of the case 16. Reed switch 2
3 is opened and closed by the magnetic action of the magnet 20. For example, when the liquid level in the gas-liquid separation chamber 12 is high and the magnet 20 is close to the reed switch 23, it is in a closed state. When the liquid level in the gas-liquid separation chamber 12 is low and the magnet 20 is separated from the reed switch 23, the open state is established. Therefore, when the gas-liquid weight ratio of the refrigerant flowing through the refrigerant pipe 11a is less than 1/9, the reed switch 23 is closed because the liquid level in the gas-liquid separation chamber 12 is high.
When the gas-liquid weight ratio of the refrigerant flowing through the refrigerant pipe 11a exceeds 1/9, the liquid level in the gas-liquid separation chamber 12 becomes low, so that the reed switch 23 is opened.

In the present embodiment, when the reed switch 23 is in the open state, it is judged that the refrigerant charge amount in the refrigeration cycle 1 has decreased to a predetermined amount, and the refrigerant shortage is detected.
When the gas-liquid ratio detection device 2 detects the shortage of the refrigerant, the warning light 26 (the warning means of the present invention) for notifying the shortage of the refrigerant is turned on through the control circuit 25 (the control means of the present invention). When the refrigerant compressor 4 is continuously operated for a predetermined time (for example, 20 minutes) or more after the refrigerant shortage is detected, the electromagnetic clutch 3 is deenergized. The control circuit 25 operates by turning on the air conditioner switch 28 using the vehicle-mounted battery 27 as a power source. The warning light 26 is
It is provided on an air conditioning control panel (not shown) provided in the instrument panel portion of the driver's seat.

Next, the operation of this embodiment will be described with reference to the operation flowchart of the control circuit 25 shown in FIG. When the electromagnetic clutch 3 is turned on (Y in step S1)
ES), it is detected via the gas-liquid ratio detection device 2 whether or not the refrigerant is insufficient (step S2). When the shortage of the refrigerant is detected, that is, when the reed switch 23 is opened, the warning light 26 is turned on (step S).
3). At this time, since the electromagnetic clutch 3 remains on, the refrigerant compressor 4 is driven by the vehicle engine. When the energized state (ON state) to the electromagnetic clutch 3 continues for a predetermined time (20 minutes) or more after the lack of the refrigerant is detected (YES in step S4), the warning light 26 is turned on and the electromagnetic The clutch 3 is turned off (energization is cut off) to stop the refrigerant compressor 4 (step S5). Note that the determinations in step S1, step S2, and step S4 are NO.
In the case of, it returns to step S1. This control is reset by turning off an ignition switch (not shown).

In this embodiment, when the vapor-liquid weight ratio of the refrigerant flowing through the refrigerant pipe 11a exceeds 1/9, the reed switch 23 is opened and it is determined that the refrigerant is insufficient. Therefore, when the warning light 26 is turned on due to the lack of the refrigerant, it still has a certain cooling capacity, and it is not possible to continuously operate the refrigerant compressor 4 for about 20 to 30 minutes in terms of durability of the refrigerant compressor 4. It is possible. Therefore, as described above, after the shortage of the refrigerant is detected, only when the electromagnetic clutch 3 is continuously in the ON state for a predetermined time (20 minutes) or more, the electromagnetic clutch 3 is operated in consideration of the durability of the refrigerant compressor 4. I decided to turn it off. By performing such control, the cooling performance can be maintained for at least a predetermined time (20 minutes) after detecting the shortage of the refrigerant.

After the shortage of the refrigerant is detected, for example, when the electromagnetic clutch 3 is turned on / off based on the information from the thermistor 29 which detects the blowout temperature of the refrigerant evaporator 10, the off time is entered. This does not result in continuous operation. In such a case, even if a shortage of the refrigerant is detected, there is no particular concern for the durability of the refrigerant compressor 4, and therefore the warning lamp 26 is turned on without turning off the electromagnetic clutch 3. Further, since the operation of the refrigerant compressor 4 is also stopped by turning off the ignition switch, it is reset by turning off the ignition switch. As described above, in this embodiment, even if the shortage of the refrigerant is detected, the cooling performance can be maintained for at least the predetermined time in consideration of the durability of the refrigerant compressor 4. The gas-liquid ratio detection device 2 for detecting the shortage of the refrigerant judges the shortage of the refrigerant by the position (height) of the float 22 floating on the liquid surface in the gas-liquid separation chamber 12, and turns on / off the reed switch 23. It is a simple structure that does only. Therefore, the cost is low and the lack of the refrigerant can be accurately detected.

In the above embodiment, the gas-liquid ratio detecting device 2 is shown as the refrigerant shortage detecting means, but a superheat switch for detecting a predetermined degree of superheat may be installed in the low pressure side pipe to detect the refrigerant shortage. .. Alternatively, the discharge pipe of the refrigerant compressor 4 may be provided with a temperature switch that operates when the temperature of the refrigerant reaches or exceeds a predetermined value to detect the shortage of the refrigerant. Also,
As a method for determining the shortage of the refrigerant, in order to prevent malfunction due to transient cycle behavior, it is determined that the switch for detecting the shortage of the refrigerant (in the present embodiment, the reed switch 23) continues to operate for a predetermined time and is insufficient. You may. In addition,
It is said that the gas-liquid weight ratio (1/9) in the gas-liquid ratio detection device 2 and the continuous ON time (20 minutes) of the electromagnetic clutch 3 after the detection of the refrigerant shortage are not limited to these values. There is no end.

[0016]

The refrigerating apparatus of the present invention can maintain the cooling performance by operating the refrigerant compressor for at least a predetermined time in consideration of the durability of the refrigerant compressor after the refrigerant shortage is detected. it can. When the refrigerant compressor operates continuously for a predetermined time, the refrigerant compressor can be protected by stopping the operation of the refrigerant compressor. The refrigerant shortage detection means only judges the refrigerant shortage based on the fact that the refrigerant filling amount in the refrigeration cycle has decreased to a predetermined amount, and does not detect the refrigerant shortage state in two stages as in the conventional case. .. Therefore, in order to maintain both the cooling performance and the protection of the refrigerant compressor as described above, two or more refrigerant shortage detecting means are used, or a refrigerant shortage detecting means for detecting a two-stage refrigerant shortage state. There is no need to complicate the structure of. As a result, the structure of the refrigerant shortage detection means is simple,
It is possible to reduce malfunctions and reduce costs.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle diagram of a vehicle air conditioner.

FIG. 2 is a sectional view of a gas-liquid ratio detection device.

3 is a cross-sectional view taken along the line AA of the gas-liquid ratio detection device shown in FIG.

FIG. 4 is a perspective view of a float.

FIG. 5 is a front view showing a fixed state of the reed switch.

FIG. 6 is a flowchart showing the operation of the control circuit.

[Explanation of symbols]

 1 Refrigeration cycle 2 Gas-liquid ratio detection device (refrigerant shortage detection means) 4 Refrigerant compressor 25 Control circuit (control means) 26 Warning light (warning means)

Claims (1)

[Claims] 1. A refrigeration cycle having a refrigerant compressor that circulates a refrigerant, and b) A refrigerant shortage is detected when the refrigerant charge amount in the refrigeration cycle drops to a predetermined amount during the operation of this refrigeration cycle. A refrigerant shortage detecting means; c) a warning means for warning when the refrigerant shortage detecting means detects the refrigerant shortage; and d) the refrigerant shortage after the refrigerant shortage detecting means detects the refrigerant shortage. A refrigeration apparatus comprising: a control unit that stops the operation of the refrigerant compressor when the compressor continuously operates for a predetermined time or longer.